In internal-combustion engines, whether diesel or gasoline powered, engine valves serve to ventilate the combustion chamber. Intake valves allow the flow of pre-mixed air and fuel into the combustion chamber. Exhaust valves allow the exit of the combustion products. Between the intake and exhaust of the air-fuel mixture and combustion products, the valves seal the combustion chamber so that the resulting explosion may drive the piston to turn the crankshaft. Operation of such valves is known in the art and generally well within the knowledge of the average professional automobile mechanic.
In order the seat the valve against the side of the combustion chamber or cylinder, valve springs are used that bias the valve against the cylinder side. Such springs generally take an average of 80 to 140 pounds pressure per square inch (psi, 5.5 E.sup.5 to 9.6 E.sup.5 Pascal (Pa)) per valve spring in order to initially unseat the valve and open the cylinder to gas flow. At full compression, the pressure increases to 300 to 600 psi (2.0 E.sup.6 to 4.1 E.sup.6 Pa) per valve spring. This increased pressure is due to the well-known quality of springs to increase their opposing force with displacement.
Such pressure comes only from one source, namely, the running engine itself. As the engine must provide the energy to open and close its own valves, such energy cannot be used to propel the vehicle, diminishing fuel economy and engine performance. It is more efficient and advantageous to have a valve biasing means which exerts a constant, not increasing, restoring force. Under such circumstances, the load upon the engine would be diminished and quicker and easier opening and closing of the valves would occur.
As opposed to liquid, hydraulic, engine valves, the use of a gas provides additional advantages not realized through liquid hydraulics. As is well-known, liquids are basically incompressible. Gases, on the other hand, are very compressible and can provide means by which a restoring force can be provided for engine valves in an internal combustion engine. The compressible nature of gases allows them to locally absorb forces that would otherwise be distributed and transmitted, creating some greater inertia with respect to the liquid hydraulic system as a whole. As gases can be locally compressed when subject to rapidly applied pressure, such distribution of the energy does not have to be immediately transmitted. This provides some inherent resiliency and certain advantages not realized by a liquid hydraulic valve system.
The device, as set forth herein, exploits these advantages to provide significant improvements upon engine performance.
Some attempts have previously been made along these lines.
______________________________________ U.S. Pat. No. Inventor Issue Date ______________________________________ 2,342,003 F. C. Meyer February 15, 1944 3,120,221 J. Lyons February 4, 1964 3,722,483 H. Overby March 27, 1973 4,484,545 J. G. Madsen November 27, 1984 4,592,313 F. H. Speckhart June 3, 1986 5,058,541 M. Shibata, et al. October 22, 1991 5,190,262 D. Woollatt March 2, 1993 5,203,535 W. E. Richeson, et al. April 20, 1993 5,224,683 W. E. Richeson July 6, 1993 5,233,950 A. Umemoto, et al. August 10, 1993 5,287,829 N. E. Rose February 22, 1994 5,339,777 H. N. Cannon August 23, 1994 ______________________________________
Some of the more pertinent patents shown above are described briefly below.
M. Shibata, et al., U.S. Pat. No. 5,058,541
This patent is directed to a valve operating system of an internal-combustion engine which includes provision for air pressure biasing the valve in a valve closing direction. Referring to FIG. 1, the assembly includes cam 8 mounted on cam shaft 7 for operation of valve 5. Numeral 8a denotes a circular base portion corresponding to a valve-closing timing of valve 5 while lobe portion 8b corresponds to a valve-opening timing of valve 5. The opening and closing of valve 5 is seen by noting valve opening 3. Piston 16 is fixed to valve shaft portion 5a and operates within sliding bore 10a in place of the usual valve spring closing mechanism. Air supply source 25 operates through check valve 23 and line 24 to pressurize chamber 13, thus biasing valve 5 in a closing direction.
F. H. Speckhart, U.S. Pat. No. 4,592,313
This reference describes a pneumatic valve return for an internal-combustion engine. The pneumatic valve return device is designed to replace mechanical springs in a cam operated valve mechanism. FIG. 1 shows a valve 14 for operation within cylinder head 10 of an internal-combustion engine. Valve 14 may be either an intake or an exhaust valve for closing a port 17 in a combustion chamber 19. Valve stem 18 is supported for reciprocating within valve guide 24 and extends through cylinder head 10 between port 17 and actuating mechanism 22. The pneumatic valve return mechanism is denoted with numeral 12 and comprises a valve return cylinder 32 with bore 34 positioned on cylinder head 10 above valve 14. Valve return cylinder 32 would be approximately the same dimensions as a conventional valve spring. Piston 76 is fitted for sliding motion within cylinder bore 34 which is pressurized through conduit 98 for biasing the valve into a closed position when required.
A. Umemoto, et al., U.S. Pat. No. 5,233,950
This patent is directed to a valve operating system for an internal-combustion multicylinder engine wherein the intake and exhaust valves are biased in their closed directions by air pressure instead of the usual valve springs. This reference is particularly interested in the pressure control valve and common relief passage and not the actual biasing of the engine valve in a closed direction as found in the previous two references discussed.
J. G. Madsen, U.S. Pat. No. 4,484,545
This reference is directed to a hydraulically actuated exhaust valve of an internal-combustion engine. The valve is biased for opening by the gas pressure found within the combustion chamber and is kept closed by an opposed hydraulic pressure. The device uses hydraulic fluid rather than the air as described in the previous patents discussed. The opening and closing movements of the exhaust valve is accomplished by means of the valve and duct arrangement shown in FIG. 2 wherein reference numeral 19 indicates the high-pressure section which operates to bias the valve in a closing direction. This high-pressure system is connected to working chamber 18 (as seen in FIG. 1) which is designated the "closing chamber" and which substitutes for the normal spring closing device found in conventional design valve systems.
W. E. Richeson, et al., U.S. Pat. No. 5,203,535
This patent is directed to a cam actuated valve assembly that includes a hydraulic spring device which provides the force to return the valve to the closed position. This system takes the place of the normal coil springs what are used in conventional valve assemblies.
J. Lyons, U.S. Pat. No. 3,120,221
This patent provides another example of a pneumatic valve return system in an internal-combustion engine. Referring to FIG. 2, valve 24 is connected to valve cylinder 28 which is pressurized through inlet 54 from supply pipe 58 in order to bias valve 24 in a closing direction.
None of these previously mentioned attempts at achieving pneumatic engine valves advantageously provide the same features as those which are set forth herein. Additionally, the present system provides means by which present internal-combustion engines may be retrofitted in order to accommodate pneumatic spring valves. Despite the ease with which retrofitting is accomplished, the present invention operates in an efficient and reliable manner in order to provide engine valves that place a diminished load upon the engine while enhancing engine performance.